Conventionally known is a linear-object handling structure in which a linear object for controlling a servomotor that operates a robot itself and a linear object for controlling a work tool that is attached to a wrist of the robot are installed in an arm of the robot.
However, some work-tool controlling linear objects do not have flexibility in the twist direction and thus cannot be installed inside the arm. Linear objects that do not have flexibility in the twist direction have been wired outside the arm (for example, see PTL 1).